Huntington's disease: Current and future therapeutic prospects.

Huntington's disease is a progressive neurodegenerative disorder for which therapies are woefully inadequate and do not prevent inevitable progression. Currently approved therapies are primarily aimed at treating chorea, but do not address the more clinically meaningful motor, behavioral, and cognitive features of the disease. However, there are a number of promising new therapies that are currently being studied in the laboratory, and in the clinic. This article will review the wide variety of therapies currently being tested, the advances in clinical trials and end points, and the many potentially relevant new targets. © 2018 International Parkinson and Movement Disorder Society.

A randomized, double-blind, placebo-controlled trial of coenzyme Q10 in Huntington disease.

OBJECTIVE: To test the hypothesis that chronic treatment of early-stage Huntington disease (HD) with high-dose coenzyme Q10 (CoQ) will slow the progressive functional decline of HD. METHODS: We performed a multicenter randomized, double-blind, placebo-controlled trial. Patients with early-stage HD (n = 609) were enrolled at 48 sites in the United States, Canada, and Australia from 2008 to 2012. Patients were randomized to receive either CoQ 2,400 mg/d or matching placebo, then followed for 60 months. The primary outcome variable was the change from baseline to month 60 in Total Functional Capacity score (for patients who survived) combined with time to death (for patients who died) analyzed using a joint-rank analysis approach. RESULTS: An interim analysis for futility revealed a conditional power of <5% for the primary analysis, prompting premature conclusion in July 2014. No statistically significant differences were seen between treatment groups for the primary or secondary outcome measures. CoQ was generally safe and well-tolerated throughout the study. CONCLUSIONS: These data do not justify use of CoQ as a treatment to slow functional decline in HD. CLINICALTRIALSGOV IDENTIFIER: NCT00608881. CLASSIFICATION OF EVIDENCE: This article provides Class I evidence that CoQ does not slow the progressive functional decline of patients with HD.

Pharmacologic approaches to the treatment of Huntington's disease.

Huntington's disease (HD) is an inherited, progressive neurodegenerative disorder characterized by chorea, cognitive impairment, and behavioral disturbances. Despite advances in diagnosis and improved understanding of HD, treatment remains difficult due to challenging symptoms and a paucity of approved therapeutic interventions. Nonpharmacologic and pharmacologic strategies have been evaluated; regarding the latter, over 80 agents of various classes have been investigated in clinical trials or examined in case reports. Symptomatic treatment, however, is generally confined to antidopaminergic agents for motor dysfunction and antidepressants for mood disorders, while treatment for cognitive dysfunction remains vacant. Several different mechanisms to modify symptoms and disease progression have been targeted in clinical trials. This article reviews some of the more common pharmacologic treatments used for HD, discusses data regarding suboptimal agents that have been tested, and surveys treatments under investigation.

Safety and tolerability of high-dosage coenzyme Q10 in Huntington's disease and healthy subjects.

Coenzyme Q10 (CoQ(10)), a potential neuroprotective compound, was previously investigated at a dosage of 600 mg/day in Huntington's disease (HD) patients and demonstrated a trend toward slowing disease progression. Higher CoQ(10) dosages may prove beneficial. We investigated the tolerability and blood levels associated with 1,200, 2,400, and 3,600 mg/day of CoQ(10) in HD and healthy subjects. Twenty-eight subjects (20 HD, 8 healthy) enrolled in a 20-week open-label trial. Subjects started on 1,200 mg/day of CoQ(10), increasing every 4 weeks by 1,200 mg to a maximum dosage of 3,600 mg/day. Monthly evaluations included review of adverse events and CoQ(10) blood levels. Twenty-three subjects (82%) achieved the target dosage of 3,600 mg/day. Six subjects (2 healthy, 4 HD) withdrew prematurely (gastrointestinal (GI) symptoms in 3, worsening HD in 2, and 1 because of a fall). All three serious adverse events occurred in a single subject, and were deemed unrelated to CoQ(10). The most common adverse events seen were GI symptoms. Mean (± SD) CoQ10 blood levels achieved over the course of the trial were as follows: 1.26 ± 1.27 µg/mL (baseline, n = 28), 5.59 ± 2.24 µg/mL (1,200 mg/day, week 4, n = 26), 6.38 ± 3.25 µg/mL (2,400 mg/day, week 8, n = 25), 7.49 ± 4.09 µg/mL (3,600 mg/day, week 12, n = 23), and 6.78 ± 3.36 µg/mL (3,600 mg/day, week 20, n = 20). CoQ(10) was well tolerated with over 80% of subjects achieving the target dosage. Dosages of 2,400 mg/day may provide the best balance between tolerability and blood level achieved. Further studies examining the efficacy of 2,400 mg/day are planned.

Effects of L-isoleucine and L-valine on hot flushes and serum homocysteine: a randomized controlled trial.

OBJECTIVE: To investigate whether L-isoleucine was effective in the treatment of hot flushes and whether L-isoleucine, L-valine, or the combination of both amino acids reduced fasting serum homocysteine. METHODS: After a 1-week baseline period, 100 postmenopausal women experiencing at least five moderate-severe hot flushes per day were randomized with equal probability to one of four groups (phase 1/phase 2): placebo/L-valine, placebo/L-valine and L-isoleucine, L-isoleucine/L-valine, and L-isoleucine/L-valine and L-isoleucine. Phase 1 was 12 weeks long, and phase 2 was 10 weeks long. Patients took five capsules by mouth, twice a day throughout the study, with each capsule containing 500 mg of compound. Data were obtained from daily hot flush diaries, fasting blood work, and several questionnaires. The primary outcome variable was the percent change in hot flush composite score from baseline to week 12. RESULTS: In phase 1 of the study, there were no significant differences between the L-isoleucine and placebo groups for any of the outcome measures. At week 12, there was a mean 13.9% decrease in hot flush composite score compared with baseline in the L-isoleucine group and a mean 25% decrease in the placebo group (P=.28). In phase 2 of the study, there was no significant change in fasting serum homocysteine levels associated with any of the amino acid therapies. CONCLUSION: L-isoleucine therapy appears to be ineffective in the treatment of hot flushes in postmenopausal women. L-isoleucine and L-valine, either alone or in combination, appear to have no effect on fasting serum homocysteine levels. CLINCIAL TRIAL REGISTRATION: ClinicalTrials.gov, (www.clinicaltrials.gov), NCT00081952. LEVEL OF EVIDENCE: I.

Translational experimental therapeutics: The translation of laboratory-based discovery into disease-related therapy.

In the past decade, there has been an increasing emphasis on laboratory-based translational research. This has led to significant scientific advances in our understanding of disease mechanisms and in the development of novel approaches to therapy such as gene therapy, RNA interference, and stem cells. However, the translation of these remarkable scientific achievements into new and effective disease-modifying therapies has lagged behind these scientific accomplishments. We use the term "translational experimental therapeutics" to describe the pathway between the discovery of a basic disease mechanism or novel therapeutic approach and its translation into an effective treatment for patients with a specific disease. In this article, we review the components of this pathway, and discuss issues that might impede this process. Only by optimizing this pathway can we realize the full therapeutic potential of current scientific discoveries and translate the astounding advances that have been accomplished in the laboratory into effective treatments for our patients.